This invention relates to a rectifying charge storage element and, more particularly, to electronic circuits fabricated on various substrates, including flexible substrates by various means including printing or other deposition techniques using organic conductors, semiconductors and insulators and other electronics material suitable for deposition and use in electronic circuits. The invention specifically relates to a power supply that extracts DC power (voltage and current) sufficient to power an electronic device from an AC input signal. The AC input signal may be derived from an inductive, capacitive, or L-C resonant circuit coupled to an external electromagnetic or electrostatic AC field. The electronic circuit thus powered may be an RFID circuit.
Most electronic circuits require a source of DC voltage with sufficient current output to power the circuit elements. Many of these circuits derive DC power by rectifying and filtering an AC power signal. Often the AC signal is provided to the circuitry by electromagnetic coupling.
For example, a passive RFID tag system must be capable of receiving power from an RFID reader to the RFID tag via inductive (H-field) or electric field (E-field) coupling, and transmitting data from the tag to the reader also via inductive or electric field coupling. Activation field frequency of RFID devices may be from under 100 kHz up to over 30 MHz if inductive or capacitive coupling to the activation source is utilized or up to multiple GHz if electric field coupling is utilized.
In current industry practice, operating power to a passive tag or other electronic circuit is derived by utilizing a rectifier device and a charge-storage device typically a rectifier diode or combination of diodes connected to a charge storage capacitor or combination of capacitors. Typically these elements are implemented as separate components within a discrete circuit or silicon integrated circuit.
New technology is developing for manufacturing circuitry such as RFID tags on flexible substrates using thin film materials such as polymer semiconductors and other substances that can be applied by techniques such as ink jet printing. A primary objective is producing devices that have operating characteristics competitive with silicon technology while approaching the economy of printing processes.
Beigel U.S. Pat. No. 4,333,072 describes an inductively coupled RFID system in which power to an RFID tag is derived from an alternating magnetic field originating in a reader-energizer coupled inductively to the tag antenna, and rectified by a rectifier in the antenna with the resulting DC charge stored in a capacitor in the tag.
Beigel, U.S. Pat. No. 5,973,598 describes an RFID tag formed on a flexible substrate by depositing or printing conductive, semiconductive and insulating substances in an operative pattern on the substrate.
U.S. Pat. No. 6,087,196 (Sturm et al) describes the fabrication of electronic circuits on flexible substrates by ink jet printing methods. U.S. Pat. No. 6,037,718 describes an organic transistor stacked on an electroluminescent display element. U.S. Pat. No. 5,915,197 describes a xe2x80x9cvaricapxe2x80x9d diode formed by silicon processes.
An object of the invention is the provision of a composite device that provides rectification and charge storage for converting AC signals to DC power supply voltages by structurally combining a rectifier diode and charge storage capacitor.
An additional object of the invention is the provision of a composite power supply which incorporates a diode rectifier and a capacitor, said rectifier and capacitor sharing a common component to facilitate the provision of the diode and rectifier in a single device.
Another object of the invention is the provision of a device of the aforementioned character which can be provided on a flexible substrate to facilitate the incorporation of the device in correspondingly flexible environments.
A further object of the invention is the provision of a device of the aforementioned character wherein various components of the device may be fabricated from organic and other conductors which constitute the interface between the conductors of the rectifier and capacitor components of the device.
Additionally, the device may incorporate a flexible substrate as an electrically operative component of the device.